Commonwealth Aircraft Corporation CA-1 / CA-3 / CA-5 / CA-7 / CA-8 / CA-9 / CA-16 / CA-20 Wirraway
In 1936, Australia sent three of her air force officers to find a suitable modern aircraft for localised license production. Lacking a respectable war-production infrastructure by the time of World War 2 and an ever-increasing Japanese presence throughout the Pacific, the Australians quickly settled on a pair of North American Aviation NA-16 trainers for evaluation and subsequent production as multirole platforms to fulfill a variety of needs.
The two examples were purchased from North American Aviation and became NA-16-1A (with fixed undercarriage) and NA-16-2K (retractable undercarriage) serving as the Australian program's prototypes. The NA-16-2K was eventually selected as the principle production model with a few subtle changes in design, these including a reinforced sub-structure consistent with the rigors of the bombing role and improved offensive/defensive capabilities by the inclusion of 2 x 7.7mm machine guns as opposed to the NA-16's sole gun. Production of the initial aircraft, designated in the Australian inventory as the "CA-1 Wirraway", was handled out of the Commonwealth Aircraft Corporation (CAC) facility at Fisherman's Bend in Victoria. First flight of the Australian system was recorded on March 27th, 1939. The first Wirraway, A20-3, was test flown by Flight Lieutenant 'Boss' Walker on 27 March 1939, and the first three RAAF Wirraways were accepted in July 1939. The selected powerplant was essentially the license produced Australian version of the Pratt & Whitney R1340 Wasp radial piston engine. By December 1940, seven aircraft were being delivered weekly, and by September 1941, 45 Wirraways per month were coming off the production line. The initial orders for 620 aircraft were completed by June 1942, but limited production continued until 1946 when the 755th Wirraway, A20-757, was delivered.
CAC designations for Wirraway orders included CA-1, -3, -5, -7, -8, -9, -10 (a bomber version which was cancelled), -10A (dive bomber), and -16. The designation CA-20 covered the conversion of Wirraways for the RAN.
The Wirraway was a low-wing monoplane assemblies with sweep back and curved wingtips, mounted well forward of amidships. Wings were attached to the oblong, rounded airframe. The engine was held in the forward most compartment and was of an air-fed radial type. The cockpit was held aft of the wings with adequate views from under the heavily framed "greenhouse-style canopy. The empennage was conventional and tapered off to form the base of the rounded vertical tail fin. Horizontal tailplanes were situated at the forward base of this single vertical fin. The undercarriage was of the "tail-dragging" arrangement dominated by the two single-wheeled main landing gear legs. While these twin assemblies retracted into the aircraft, the diminutive single-wheeled tail wheel did not and remained exposed whilst the aircraft was in flight. Crew accommodations amounted to two personnel made up of the pilot and an observer. Armament included a pair of 7.7mm Vickers GO machine guns while 2 x 250lb or 500lb bombs could be carried.
The Wirraway was fitted with the Pratt & Whitney R-1340 series, 9-cylinder, supercharged, air-cooled radial piston engine producing 600 horsepower and mated to a three-blade Hamilton Standard Constant speed propeller. Top speed was roughly 220 miles per hour with a cruise speed of just 155 miles per hour. Fuel was limited to 116-US gallons in wing fuel tanks with a pair of 11-US gallon reserve fuel tanks. Dimensionally, the aircraft sported a wingspan of 43-feet even with a length of 27 feet, 10 inches. Her height was 8 feet, 8 3/4 inches. When empty, the Wirraway displaced at 3,992 lbs and 6,595lbs for a maximum take-off weight.
The Wirraway was produced in seven major marks beginning with the CA-1 of which 40 were produced. The CA-3 was wholly similar to the CA-1, just assigned a different designation due to the nature of the Australian government production contract. This mark numbered 60 examples in all. In fact, the CA-5, CA-7, CA-8 and CA-9 were all also similar in scope to the original CA-1. The CA-5 was produced in a further 32 examples. The CA-7, CA-8 and CA-9 marks were produced in totals numbering 100, 200 and 188 examples respectively. The CA-10A was an uncompleted bomber proposal, fitted with dive bomber wings but the CA-3, CA-5, CA-7 and CA-9 models were ultimately modified with such wings to become the CA-20 mark. CA-16, the last production Wirraway, was built to the tune of 135 examples before the last rolled off of the Commonwealth assembly lines and these represented the largest modification since the inception of the CA-1. The CA-16 fitted a pair of dive brakes and carried a larger bombload for dive bombing sorties, in many ways making her the "definitive" breed of the family line. The last was delivered on 30 November 1953
Australia maintained the largest collection of Wirraways and these served with the Australian Air Force squadrons No.4, No.5, No.12, No.21, No.22, No.23, No.24 and No.25. The Australian Navy Fleet Air Arm utilized 17 of the type with squadrons No.723 and No.724. The RAN first aircraft was delivered on 24 November 1948. The United Kingdom's Royal Air Force fielded one squadron (Y Squadron) of Wirraways in Malaya from 1941 to 1942, this being formerly the No.21 Squadron of the RAAF. The United States operated the Wirraway in limited numbers and only for a brief time with its HQ Flight as part of the 5th Air Force.
In 1940-41, camouflaged Wirraways were deployed to forward bases in Malaya (No 21 Squadron) Rabaul (No 24 Squadron), and Darwin (No 12 Squadron). On 6 January 1942, Flight Lieutenant B. Anderson of No 24 Squadron became the first RAAF pilot to engage in air-to-air combat in the South-West Pacific, when his Wirraway intercepted a Kawanishi (Mavis) flying-boat over Rabaul on January 6th, 1942 with no confirmed kill.
Two weeks later, on 20 January 1942, the Rabaul Wirraways achieved fame when eight aircraft, including A20-177, piloted by Sergeant W. Hewett, engaged a force of over 100 Japanese fighters and bombers. Although hopelessly outclassed by enemy aircraft, the Wirraway remained in the front line as a stop-gap fighter, and on 26 December 1942, Wirraway history was made when Pilot Officer J. Archer, in A20-103, succeeded in shooting down a Mitsubishi A6M Zero fighter near Gona.
Additional actions placed Wirraways over the skies of New Guinea but these were primarily used as ground attack platforms in support of ground forces in the region. The Wirraway continued in this respect until Curtiss P-40 Warhawks could be delivered in sufficient numbers from America and CAC could bring online its "Boomerang" dedicated fighter platform.
A Wirraway was used in 1947-48 by No 81 Wing while on duty with the British Commonwealth Occupation Forces in Japan.
Despite her early-war origins, the Wirraway continued on in the post-war world, primarily back in form with her dedicated trainer roots. The Royal Australian Navy would retire their Wirraways in 1957, replaced by the jet-powered de Havilland Vampires from Britain, while the Royal Australian Air Force continued Wirraway use up until 1958 - her last flight being formally recognized on April 27th, 1959.
After WW2 a number of Wirraways were converted to agricultural use, leading to development of the CA-28 Ceres agricultural aircraft.
CAC CA-16 Wirraway
Engine: One 600 hp (448 kW) Pratt & Whitney R-1340-S1H1-G Wasp 9-cylinder radial
Weight loaded: 2991 kg / 6,595 lb
Propeller: Hamilton Standard Constant Speed, All metal, three blade
Fuel: Aviation Gasoline 100 Octane
Wing Span: 13.11 m / 43 ft 0 in
Wing Area: 255.75 sq. ft / 23.76 sq. m
Length: 8.48 m / 27 ft 10 in
Height: 2.66 m / 8 ft 8 in
Empty weight: 3,992 lb / 1,811 kg
Maximum Takeoff weight: 6,595 lb / 2,991 kg
Wing Tank Capacity: 97 Imp Gal / 441 Ltr / 116 U.S. Gallons
Reserve Tank Capacity (2): 9 Imp Gal / 41 Litres / 11 U.S. Gallons
Initial Rate of Climb: 1,950 ft per minute
Max. speed: 354 km/h / 220 mph / 191 knots
Cruise Speed: 135 knots / 155 mph / 250 km/h
Ceiling: 7010 m / 23000 ft
Range: 1159 km / 720 miles
Armament: 2 x 0.303 Vickers machine guns, 2 x 500 lbs and 2 x 250 lbs if no observer carried